467
FXUS02 KWBC 311933
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
333 PM EDT Sun May 31 2026

Valid 12Z Wed Jun 3 2026 - 12Z Sun Jun 7 2026

19Z Update: The 12Z model guidance suite features decent synoptic
scale agreement across the central and eastern U.S. for the middle
of the week. However, there appears to be below average confidence
across the East Coast region with the evolution of the upper trough
and its potential role in the development of an offshore low
pressure system. The UKMET stands out as a western outlier with the
low developing much closer to the NC coast compared to the other
guidance, whereas the CMC is well to the northeast and has more
high pressure where both the GFS/ECMWF favor a low. As a result,
changes to the NBM were necessary to lower QPF along the Mid-
Atlantic coast for Wednesday into Thursday, and thus keeping the
significant rainfall offshore. Therefore, the preference is
towards a GFS/ECMWF compromise for Wednesday through Friday.

Looking ahead to next weekend, the guidance agrees well on a more
amplified trough settling in across the Pacific Northeast and then
the northern Rockies, and thus small downward adjustments in
temperatures from the NBM were made for this region. Across the
Northeast, the ECMWF is less amplified with an upper trough over
New England, but agrees well with the other guidance on the ridge
across the Southeast states. The ensemble means were gradually
raised to about 40% by next Sunday, and the previous forecast
discussion is appended below for reference. /Hamrick
-------------------

...Overview...

Transient shortwave energy will propagate across the northern tier
and into Ontario during the medium range. This system will likely
generate storms across the Northern Plains and Upper Midwest late-week.
Downstream ridging will spread above average temperatures from the
Central U.S. late next week into the East by the weekend.
Shortwave impulses out of Mexico will generate additional shower
and thunderstorm activity across portions of the Southern/Central
Plains during the medium range. A potent mid-level low enters the
Pacific Northwest on Friday, bringing renewed chances for rain to
the region next weekend.


...Guidance/Predictability Assessment...

Non Canadian models are in reasonably good agreement regarding the
evolution of the overall synoptic pattern across the lower 48
between Wednesday and next Sunday. The Canadian mainly deviates
from consensus regarding the evolution of the East Coast trough
mid-to-late next week. Models are a bit uncertain as to the
intensity of the approaching East Pacific low late-week, but tend
to agree on the timing of it.

A general model blend consisting of the available non-CMC
deterministic and Ai guidance was used in the blend on day 3. The
GEFS was introduced on day 4 to mitigate some of the differences in
the amplitude of the Southwest energy. The Euro and GFS suites are
favored in the blend through the rest of the medium range period
due to good clustering on the synoptic pattern.


...Weather/Hazards Highlights...

A slow moving surface low pressure system will focus scattered to
numerous showers and thunderstorms over portions of the Northern
Plains and Upper Midwest/Great Lakes on Wednesday and Thursday.
Some storms may produce isolated instances of flash flooding, which
is why a Marginal Risk of excessive rainfall remains in effect for
portions of the Plains and Upper Midwest. Meanwhile, a weak mid-
level disturbance propagating northward across the Southern High
Plains will also act as a forcing mechanism for more thunderstorm
activity across portions of the Central and Southern Plains. A
Slight Risk of excessive rainfall remains in effect for portions of
southeastern New Mexico and into western Texas on Wednesday.

A deep upper-level low will bring rain to the Pacific Northwest
late this week and into the weekend. Some showers may spill over
into the Northern Rockies/High Plains by Saturday. Elsewhere, a
weak quasi-stationary front draped across Florida will generate
daily showers and thunderstorms over the peninsula.

A ridge centered over the Midwest will promote broad southerly flow
into the Eastern half of the country late next week. Temperatures
will gradually increase over portions of the Midwest and East Coast
as the ridge shifts eastward, with much of the Mid-Atlantic Coast,
in particular, possibly experiencing some heat risk impacts by the
weekend as lows struggle to drop into the 60s in some places.

Kebede


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast, excessive rainfall outlook,
winter weather outlook probabilities, heat indices and Key Messages
are at:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw








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